Lakeland Gases Review

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At the same temperature and pressure, 1.0 literof CO(g) and 1.0 liter of CO2(g) have

A) equal masses and the same number of molecules

B) equal volumes and the same number of molecules

C) different masses and a different number of molecules

D) different volumes and a different number of molecules

Question 1

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• Think of PV = nRT for both gases to determine which variables must be the same or different

Correct!

• If the two gases have the same pressure, volume and temperature then their number of moles must be the same. This means the same number of particles.

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Which graph shows the pressure-temperature relationship expected for an ideal gas?

Question 2

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• As temperature increases the molecules move faster.

Correct!

• As temperature increases the molecules gain more energy and therefore run into the sides of the container holding the gas more often. This causes an increase in pressure.

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A 3.00-liter sample of gas is at 288 K and 1.00 atm. If the pressure of the gas is increased to 2.00 atm and its volume is decreased to 1.50 liters, the Kelvin temperature of the sample will be

A) 144 K B) 432 K

C) 288 K D) 576 K

Question 3

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• Use the combined gas law to solve for the temperature

Correct!

• P1V1/T1 = P2V2/T2 (3)(1)/288 = (2)(1.50)/T2

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If 4.00 atm of oxygen gas, 3.00 atm of hydrogen gas, and 1.00 atm of nitrogen gas are combined in a closed container, what is the total pressure in the container?

A) 1.00 atm B) 3.00 atm

C) 4.00 atm D) 8.00 atm

Question 4

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• Dalton’s Law of Partial Pressure states that the total pressure is equal to the sum of the partial pressures

Correct!

• 4.00 atm + 3.00 atm + 1.00 atm = 8.00 atm

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What is the volume, in liters, of 576 grams ofSO2 gas at STP?

A) 101 B) 216

C) 202 D) 788

Question 5

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• This problem requires you to use the ideal gas law. Make sure to convert grams to moles.

Correct!

• PV = nRT (1 atm)V = (576x1/64)(0.0821)(273)

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As the temperature of a given sample of a gas decreases at constant pressure, the volume of the gas

A) Increases B) Decreases

C) Remains the same D) Impossible to tell

Question 6

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• Volume and temperature have a direct relationship

Correct!

• As temperature decreases, volume decreases.

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The pressure on a 200-milliliter sample of CO2(g) at constant temperature is increased from 600 torr to 1,200 torr. What is the new volume of the gas?A) 100 mL B) 300 mL

C) 400 mL D) 600 mL

Question 7

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• Use Boyles law to solve the problem. You do not need to convert any units.

Correct!

• P1V1 = P2V2 (600)(200) = (1200)V2

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If 60. liters of hydrogen gas at 546 K is cooled to 273 K at constant pressure, the new volume of the gas will be

A) 120 L B) 40 L

C) 30 L D) 20 L

Question 8

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• Use Charles Law to solve the problem

Correct!

• V1/T1 = V2/T2 60/546 = V2/273

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A sample of gas is held at constant pressure. Increasing the kelvin temperature of this gas sample causes the average kinetic energy of its molecules toA) decrease and the volume of the gas sample to decrease

B) decrease and the volume of the gas sample to increase

C) increase and the volume of the gas sample to decrease

D) increase and the volume of the gas sample to increase

Question 9

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• More heat will increase the speed of the molecules.

Correct!

• An increase in heat causes the molecules to speed up and push out on the sides of the container. This causes an increase in volume.

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A gas occupies a volume of 444 mL at 273 K and 79.0 kPa. What is the final kelvin temperature when the volume of the gas is changed to 1880 mL and the pressure is changed to 38.7 kPa?

A) 31.5 K B) 566 K

C) 292 K D) 2360 K

Question 10

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• Use the combined gas law

Correct!

• P1V1/T1 = P2V2/T2

• (79)(444)/273 = (1880)(38.7)/T2

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What is the total volume occupied by 132 grams of CO2(g) at STP?

A) 22.4 L B) 44.8 L

C) 33.6 L D) 67.2 L

Question 11

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• Use PV = nRT and be sure to convert grams to moles

Correct!

• PV = nRT (1)V = (156 x 1/44)(0.0821)(273)

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As the volume of a fixed mass of a gas increases at constant temperature, the pressure of the gas

A) increases B) decreases

C) Remains the same D) Not enough information

Question 12

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• Pressure and volume are inversely related

Correct!

• As the volume increases, pressure decreases

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Which temperature change would cause the volume of a sample of an ideal gas to double when the pressure of the sample remains the same?

A) from 200°C to 400°C B) from 400°C to 200°C

C) from 200 K to 400 K D) from 400 K to 200 K

Question 13

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• Remember that temperatures need to be in Kelvin when using the gas laws.

Correct!

• As volume increases so does temperature. 200 K to 400 K is a double in temperature, so it also doubles the volume.

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A cylinder with a tightly fitted piston is shown in the diagram below.

As the piston moves downward, the number of molecules of air in the cylinderA) increases B) Decreases

C) Remains the same D) Impossible to tell

Question 14

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• Think of the ideal gas law. Which variables change with a change in pressure and volume.

Correct!

• The number of molecules remains the same since no gas is able to escape a sealed container.

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A gas occupies a volume of 40.0 milliliters at 20°C. If the volume is increased to 80.0 milliliters at constant pressure, the resulting temperature will be equal to

Question 15

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• Remember that we use Kelvin for the gas laws. Volume and temperature are inversely proportional.

Correct!

• V1/V2 = T1/T2 40/80 = 293/T2

• so T2 = (80)(293)/(40)

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